Time service synchronizing system



Dec. 5, 1933. G w JANSON I 1,937,894

TIME SERVICE SYNCHRONIZING SYSTEM Suvcntor utmrncg Dec. 5, 1933. G. w. JANsoN TIME SERVICE sYNcHRoNIzING SYSTEM Filed Nov. 8, 1930 9 Sheets-Sheet 2 l y n ill Dec. 5, 1933. C G w JANSON 1,937,894 y TIME SERVICE SYNCHRONIZING SYSTEM Filed Nov. 8, 1930 9 Sheets-Sheet 3 IlllllllilllIllIlV//l///` Slwcntor Gewjye 71h72 Joa Mimi Dec. 5, 1933. G. w. JANsoN 1,937,894

TIME SERVICE SYNCHRONIZING SYSTEM Filed Nov. 8, 195o 9 sheets-sheet 4 G mtorncg Dec. 5, 1933.- v .GT wyJANsoN 1,937,894

TIME SERVICE SYNCI-IRONIZINGl SYSTEM Filed Nov. 8,- 1930 9 Sheets-Sheet 5 v Snventor 620736 52726072 Gttorneg G. W. JANSON TIME SERVICE SYNCHRONIZING SYSTEM' Dec.- 5, 1933.

Filed Nov. 8,. 1930 9 SieecQs-Sheet I 6 CryeozyeA )Wg/ntrax@ Dec. 5, 1933. Q w, JANSQN l I 1,937,894

TIME SERVICE SYNCHRONIZING SYSTEM Filed Nov.l 8, 1930 9 Sheets-'Sheetr '7 Je Z@ 31wentor Dec. 5, 1933. G'. w. JANSON 1,937,894

TIME SERVICE SYNCHRONIZING SYSTEM Filed NOV. 8, 1930 9 Sheets-Sheet' 8 W' NWN "i fl' /HHHHHMMNHN[MUMHIIHHIHIlI/Hllllllllllnw' G/O/jge Wfamron/ Dec.5,19s3. @.wJANsQN 1,937,894

TIME SERVICE SYNCHRONIZING SYSTEM l Patented Dec. 5, 1933 PATENT or-'F1 f TIME sERvIcEsYNcHRoNIzING SYSTEM George W. Janson, Nutley, N. J., assigner to' The Y Western Union Telegraph Company, New York, N. Y., a corporation of New York Application November 8, 1930. Serial No. 494,425

6 Claims. (Cl. 58-35) This invention relates to electric clock systemsl wherein a master clock controls the operation of a number of subscribers clocks and wherein each subscribers clock having any variation from synchronism with the master clock is corrected at predetermined time intervals, in the present case at intervals of one hour, by synchronizing impulses transmitted under control of the master clock.

In devices of this character it is desirable that as little work as possible shall be imposed on the master clock in addition to its time keeping function and that the operation of the circuit closers necessary for closing the synchronizing circuits through the subscribers clocks shall be eiiected by separate motor means. It is necessary for a relatively high voltage to be used in the subscribers circuits but it is not desirable that the mechanism of the master clock shall be used for directly closing and opening anybut very low tension circuits. A normally idle electric motor is found desirableto actuate the circuit closers for the subscribers clock circuits and, in order to have this motor operate at uniform speed and in synchronism with the master clock it is desirable to provide that the motor shall not actuate;

these circuit closers until sufllcient time has elapsed after the motor starts to permit it to acquire its normal speed.

Since all clock mechanisms are subject to variation from standard time it sometimes happens, in a system of this character, that the master clock will vary from standard time. In the present instance such standard time is assumed to be that of the Naval Gbservatory at Washington, D. C. from which time signals are transmitted telegraphically at noon each day. vIt is accordingly desirable that means shall be provided for checking the master clock of such a system against the Washington time signals and for adjusting certain of the contacts of the subscribers circuits to correct any error in synchronism between the subscribers clocks and standard time, while temporarily leaving the master clock in a synchronous condition.

It-is also desirable. in a system of this character that means should be provided for testing the several subscribers circuits without inter-- fel-ing with the operation of the synchonizing means. i

The main objects of the present invention are accordingly 'to provide an eicient apparatus for synchronizing a number of subscribers clocks.

with a masterv clock by synchronizing impulses transmitted to the subscribers clocks at predetermined time intervals; to eliminate to the greatest practicable extent all duty from the maser clock other than its duty, as a time keeper; to effect the operations of closing and opening the synchronizing circuits by an electric motor; to provide means whereby the motor will normally remain` idle and out of circuit but will be connected in a motor circuit and allowed to run idle until it has acquired its standard speed andV thereafter connecting it to the circuit closing means for the synchronizing circuits; to provide means for checking and correcting errors due to variation of the master clock'from standard time; and to provide means for testing the several subscribers circuits.

With the above and other objects in view cer tain embodiments of the invention will now be described in detail and specifically claimed, reference being had to the accompanyingH drawings, wherein:-

Figure 1 is a perspective View ofv one form of the apparatus, certain parts of the casing being broken away to show parts of the apparatus.

Figure 2 is a plan View of the gearing in the lower partof the casing in this form of the apparatus.

Figure 3 is a view in section on the line 3-3 of Figure 2, certain of the parts being shown in elevation and others to the rear being omitted.

Figure 4 is a plan View on an enlarged scale and partly in section, showing the subscribers clock circuitclosers used herewith. Figure 4B is a modified arrangement of the 'clock circuit closers shown in Fig. 4. Y

Figure 5 is a section on the line 5-5 of Figur 2, parts behind the section being omitted.

Figure 6 is a section on the line 6-6 of Figure 5.

Figure i is a view of certain parts of Figure 6 taken from the left of that figure and showing the parts at the instant the motor drive becomes effective.

Figure 8 is la section on the line `8---8 of Figure 5.

Figure 9 is a perspective view of the upper part of a certain drive shaft used herewith.

Figure 10 is a diagrammatic view of the circuits used in this form.

Figure 11 is a view similar to Figure 2 but showingan arrangement of gearing as used in a modified form of the invention.

Figure 12 is a section on the' line 12-12 of Figure l1.

Figure 13 is a diagram of the circuits used i this form of the invention.

In the form of the invention shown in Figures 1 to 10 inclusive there is provided a casing having a lower section 10 and an upper section 11. A motor l2 is provided which is here shown as exterior of the casing, the motor shaft being connected .by a. universal coupling 13 with a drive shaft 14, which extends into the casing section 10 and has its inner end journalled in a bearingy 15. A worm 16 is keyed or otherwise fixed on the shaft 14 adjacent the bearing 15. At 17 is a vertical shaft Whereon is rotatably mounted a sleeve 18 which is provided at its lower end with a worm wheel 19, wherewith the worm 16 meshes. A lower clutch member 20 is fixed on the upper end of the sleeve to revolve therewith. A rectangular head 21 is fixed on the upper end of the shaft 17 and an upper clutch member 22 has a central opening fitting this head to slide vertically thereon. An armature 23 is secured to the upper face of the clutchmember 22 and slides through a guide ring 424 which is supported on a. bracket 25 and an electromagnet 26 is supported by this bracket so that, when energized, this magnet raises the clutch member 22, opening the clutch and when deenergized allows the member 22 to fall, closing the clutch, so that the shaft 17 and sleeve 18 will revolve together. A wedge lug 27 (see Fig. 7) is formed on the under side of the ring and is adapted to enter a V-notch 28 in the upper face of the member 22 upon the clutch being opened, thus causing the shaft 17 to be held at rest always in the same position, it being understood that the arrangement of the motor and its connections and circuit closers is such that the shaft 17 will always stop in such positionthat the wedge 27 will always enter the notch 28 upon energization of magnet, 26,` so that any slight variation from true starting position of shaft 17 will thus be automatically corrected. The reason for the necessity of this will be apparent by what follows hereinafter. A 'pinion 29 is fixed on the lower part of shaft 17 and meshes with a gear 30 fixed on a vertical shaft 31 and having a pinion 32 formed integrally therewith. A gear 33 isl revolubly mounted on the shaft 17 and is in mesh with the pinion 32. At each side of the apparatus is a vertical shaft 34 on the lower end of which is fixed a gear 35 wherewith the gear 33 meshes. This train thus forms 'a reduction gear for driving the shafts 34 upon rotation of the shaft 17.

A sleeve 36 is revolubly mounted on the shaft 31 and keyed on this 4sleeve is a -bevel gear 37 wherewith meshes a bevel pinion 38 carried on the inner end of a horizontal shaft 39 which projects forwardly through the front of the casing section 10. A manipulating knob 40 bearing a radially divided dial 41 is fixed on the outer end of shaft 39 to rotate the same. A gear 42 is formed integrally with the gear 37 and meshes with a gear 43 revolubly mounted on one of the shafts 34 and having a gear 44 formed integrally therewith. A gear 45 is revolubly mounted on the- ,shaft 17 and is in mesh with the gear 44. A gear 46 is fixed to the gear 45 andmeshes with gears 47 fixed on sleeves 48 which arerevolubly mounted on respective shafts 34 thereby providing a reduction train between sleeve 36 and sleeves 48.

A disk 49 is fixed on the upper end of the sleeve 36 and revolves in a suitable opening in the top of the casing 11. A pair of contact closing cams 50 and 51 are spaced one below the other on the upper end of the shaftv 31, this upper end pro- 'jecting-well above the disk 49. A fixed contact member 52 and a movable contact member 53 project up from the disk 49, the member 53 lying in the path of the upper cam 50. A second pair of contact fingers 54 are supported on a bracket 55 fixed to the casing and lie in the path of the lower cam 51.

An elongated and iiuted contact closing cam 56 is fixed on the upper end of each shaft 34 to revolve therewith. A disk 57 is fixed on the upper end of each sleeve 48 and supports a contact supporting frame having a series of vertical bars 58 each carrying a series of pairs of contact fingers 59, the arrangement of the parts being such that rotation of the cam 56 causes simultaneous closing of all contacts 59.

Considering now the circuit connections for this form of the invention as shown in Fig. 10, there is provided a master clock 60 having circuit closing cams 61 and 62 fixed on a suitable staff of the clock work mechanism, being preferably fixed on the minute staff which makes one complete revolution every hour. 'A spring contact circuit closer 63 is positioned in the path of the cam. 61 and the arrangement of this cam and contact is such that the contacts are closed ten seconds before the hour and -held closed for eight seconds. A second pair of spring ngers forming a circuit closer 64 is arranged in the path of the cam 62 andthe arrangementof this cam and circuit closer is such that the contact is closed at twenty seconds before the hour and held closed for twenty seconds to open at the hour. A conductor 65 connects the circuit closers 63 and 64 in series and a conductor 66 -leads from the circuit closer 63 to one terminal of a local battery 67. A conductor 68 leads from the remaining terminal'of this battery to one terminal of the closing magnet 69 of a motor circuit relay. A conductor 70 leads from magnet 69 to the magnet 71 of a lifting magnet circuit relay and a 1 conductor 72 connects this magnet 71 with the circuit closer 64. A suitable source of current for the motor here indicated by the generator 73 is provided, one terminal of the generator being grounded at 74 anda conductor leads from the generator 73 to the motor 12. A conductor 76 leads from motor 12 to the movable contact 77 of the motor circuit relay, a contact 78 being engaged by this contact upon energization of magnet 69. A conductor 79 connects the contact 78 with a ground wire 80. Also a conductor 81 leads from the conductor 75 to one terminal of magnet 26, the other terminal of said magnet being connected to a conductor 82 which leads to the movable contact 83 of the magnet circuit relay. A contact 84 is engaged by this contact 83 upon energization of magnet 71 and is connected by a conductor 85 to contact 77. A holding magnet 86 is connected by a conductor 87 to the feed wire 75 and a conductor 88 connects this holding magnet to the contact 77. A conductor 89 connects conductor 87 to one side of short eircuiting circuit closer 54 -and a conductor 90 connects the other side of this circuit closer to conductor 88. The circuits just described effect closing and opening of the motor and lifting magnet circuits in timed lrelation as follows: At twenty seconds before the hour circuit closer 64 is closed and at ten seconds before' the hour circuit closer 63 is closed, the cams 61 and 62 respectively effectingl such closing. Current will now fiow from battery 67 through conductor 66,4

69, and conductor 68 to battery 67. This4 will close contacts 77- and 83 on contacts 78 and 84 respectively. Consequently current will flow from source 73 through conductor 75, conductor 75', motor 12, conductor 76, contact 77, contact 78, conductor 79 to ground wire 80. Current will also iiow from conductor 75 through conductor 81, magnet V26, conductor 82, contact 83, contact 84, and conductor 85 to contact 77 and thus to the ground as before. Furthermore current will fiow from feed 75 through conductor 87, magnet 86 and conductor 88 to contact 77 and again to the ground so that the holding magnet 86 is energized. The magnet 26 being thus energized the clutch member 22 is raised so that the sleeve 18 is free to revolve on shaft 17. This also starts motor 12 which is allowed time to attain its rated speed. At two seconds before the hour the cam 61 releases the circuit closer 63, opening the circuit through the magnets 69 and 71. This permits contact 83 to open and thus deenergize the magnet 26 which allows clutch member 22 to drop and engage clutch member 20 and thus cause shaft 17 to revolve with sleeve 18 since the holding magnet 86 is not at this time deenergized and the motor circuit is maintained. As the shaft 17 revolves the shaft 31 will be driven by the reduction gear as will also the shafts 34.

A number of relay'windings 91 are connected in multiple to the supply 75 and to a conductor 92 which leads to the fixed contact 93 of a relay having a movable contact 94 and' an actuating magnet 95, one terminal of which is grounded, as is also the contact 94. A conductor 96 connects supply conductor 75 with` contact 53 and a conductor l97 connects contact 52 with a bell 98. A

conductor 99 leads from this bell to a contact ofa testing jack.' A contact 101 is normally engaged by the contact 100 and is connected by a conductor 102 with the fixed contact 103 of a battery clock relay 108. This relay is controlled by a battery clock 104,/actuating a circuit closing cam 105 at five seconds before the hour to engage a movable contact 106 and close it on a fixed contact 107 connected through the relay winding 108 to a battery 109 which is also connected to contact 106. A movable armature contact 110 is moved by the energization of the relay windingV 108 to engage thecontact 103, the contact 110 being connected by a conductor 111 with magnet 95. As above noted, the contact 110 is closed on the contact 103 at five seconds before the hour. The cam 50 is timed to close the contact 53 on the contact 52 two seconds after the sleeve 18 is clutched to the shaftv 17 `being thus exactly on the hour as given by the master clock provided the latter is in correct time, provision being made as will be hereinafter described for eecting closing of contacts 53 and -52 exactly on the true hour. Current will now flow from supply 75 through conductor 96, contact 53, contact 52, conductor 97, bell 98, conductor 99, contact 100, contact 101, conductor 102, contact 103, contact 110, conductor 111 and magnet 95 to the ground. This will effect closing of contact 94 on contact 93 and current will flow from supply 75 through relay windings 91, conductor 92, contact 93 and contact 94 to the ground. It will be noted that an audible signal is given by the bell upon closing of contacts 53 and 52. It will be noted that the high voltage generators 113 are connected to the panel 117 containing the terminals of the clock circuits, only ve seconds before the hour under the control ofthebattery clock. All of the high voltage circuits and'controlling relays should be isolated entirely from the master clock vand its circuits and hence this high voltage apparatus is placed in a different location and is under the control of a separate battery clock. The subscribers clocks 112 are connected in series in each of a number of circuits, the setting mechanism for only one of these'clocks being here shown. Because of the variation in lengths I and resistances of the different circuits it is p'referred to provide power sources 113 of different l voltages each feeding to a separate bus bar 114 from whence individual circuit conductors 115 lead through circuit closers` 116, controlled by. the respective windings 91, to a distributing panel 117 from whence run the conductors of the individual clock circuits one of which is shown at 118. The conductor 118 leads to one of the circuit. closers 59 and a conductor 119 leads from `this circuit closer 59 toa test'jack contact 120 on which 'is normally closed a contact 121. A conductor 122 connects this contact 121 in series through the clock setting magnets 123 of the subscribers clocks'112 and has its terminal endl grounded. The magnet 123 in each.clock.is 'arranged to actuate a lever 124 when energized and this lever carries a wedge 125 which engages a V-shaped setting groove in a disk 126 nxed on the minute staff of the respective clock 112 so that if the minute hand of the clock is not in its true position itis moved by this means to position on the sixty minute mark.k Tracing this circuit it will be seen that, upon closing the con- `tact 94 on contact 93 and consequent energization of coils 91 as before described, current will ow from source 113 through bar 114, conductor 115 andcircuit closers 116 to connecting panel 110 117 and from thence through conductor 118circuit closer 59, conductor 119, contact 120, contact 121, conductor 122 and magnet 123 tothe ground. A variable resistance 127 is preferably inserted in conductor 122 so that the several clock 115 circuits may be balanced. Also a suitable spark preventing device 128 may be connected to the motor circuit.

IThe cam 51 is arrangedto close the circuit closer 54 temporarily at two seconds after the 120 hour. Closing of the circuit closer 54 elects short circuiting of the current through Athe holding magnet 86 since current will now ow from feed 75 through motor 12, conductor 76, conductor 88,

conductor 90, circuit closer 54, conductor 89 and 125- conductor 87 to ground wire 80. The contact 77 will now open from contact 78. Upon the opening of contact 77, the .circuit through the motor will be broken and the latter will stop. The cams 50 and 51 are arranged to make one revolution in four seconds so that the circuits previously described as controlled by these cams are broken very shortly after the closing thereof. Thus the magnet 123 isenergized only momentarily andl the operation of the clocks 112 is not perceptibly 135 checked.

Provision is made for testing the integrity of the circuits through the subscribers clocks. To effect this a conductor 129 leads from conductor 118A at a point close to the circuit closer 59 and extends to a sleeve contact 130 of the test jack having the contact 121. A conductor 131 connects the conductor 122 withfan automatic testing device (not shown). A plug 130 carrying a pair of conductors is connected to a testing device, (not shown), and is adapted lfor insertion in the test jack to bridge contacts 130 and 121. A pair of contacts 132 and 133 of a test switch are arranged t'o be moved apart by a key 134 to engage,

Irespective contacts 135 and 136. Contact 135 is 150 connected by a conductor 137 with conductor 97 tact 132 and a conductor 140 connects conductor` 111 with contact 133.- Upon the key 134 being depressed current will flow from feed 75 through conductor 96,` conductor 139, contact 132, contact 135, conductor 137, conductor 97, bell 98. conductor 99, conductor 138, contact 136, contact 133, conductor 140, conductor 111 and through magnet 95 to ground thus closing contact 94 on contact 93. The ringing of bell 98 thus gives evidence of the integrity of this circuit, andcloses the relay circuit closers 116. Upon insertion of the plug 130 into the test jack, current will flow from bus bar 114, through uppermost conductor 115, armature 116 of the right hand relay, switch- "board panel 117, conductor 118, conductor 129,

ring contact 130 of the test jack, plug 130 vand an ammeter connected thereto, test jack contact 121, conductor 122 to the clock magnets in the line,

which thus indicates the integrity of the cloclry circuit.

Provision is also made for detecting variations between true time as received from the Naval Observatory and the time as given by the master clock 60. To this end the circuit closer 63 is arranged to close at fty-seven minutes and fifty seconds, fifty-eight minutes and fty seconds and tacts 100 and 143 apart and bring the contact' 160 into engagement with contact 141. A contact 145 is arranged in the path of movement of contact 143 and a conductor 146 connects contact 145 and conductor, 65. The key 144 is depressed shortly before the fifty-seven minutes and fifty seconds time above mentioned. At that time circuit closer 63 is closed and current will flow from battery 67, conductor 66, circuit closer 63, conductor 65, conductor 146, contact 145, contact 143, a conductor 147, conductor '12, magnet 71, conductor 70, magnet 69 and conductor 68 back -to the battery. This effects lclosing of contacts 77 and 83 on contacts 78 and 84 respectively and starts the cycle of operations previously described. However, the opening of contact 100 from contact 101 and its closing on contact 141 provides a somewhat different circuit path since the magnet 123 is not energized but current flows from feed through conductor 96, contact 53, contact 52, conductor 97, single stroke bell 98, conductor 99, contact 100, and contact-141 to ground 142. Due to the timing of the cycle as befor described the cam 50 closes this circuit and rings the bell exactly two minutes before the hour as given by the master clock. This signal is compared with the 'Washington time signals as given by a bell or recorded on a chronograph. If any variation from Washington time is found to exist the knob 40 is turned in the `proper direction to move the contacts 53 and 52Y around the -cam 50 and to correspondingly move the contacts 59 around the cam 56. A second test may be made in a similar manner at one minute before noon and any error still existing may then be corrected in a similar manner. Obviously the cam 51 will restore the parts to normal condition at two seconds after each test so that, at the noon hour the setting of the subscribers clocks 'energization of magnet 162 to engage a fixed will be effected Just as though lno test had been made ,except that the setting cycle will occur at true Washington neon even if the master clock indicates some variation from noon. This vari-.- ation from the master clock will of course be maintained for subsequent hourly settings until the master clock has been adjusted to conform to VtVashington time whereupon the knob 40 is rese 11, 12 and 13 is similar in construction to the form just described. Also many of the circuit connections are identical with those of the first form. Accordingly the parts of thisl second form vcorresponding to those of the first form have received like reference characters and only those parts vwhichv 'differ will be specifically described.

The shaft 14 is used in this form but, in addition to the worm 16 is extended to carry this shaft well toward the left hand end of the cas- `ing 10. The worm 16 drives the sleeve 18 and The form or the invention shownm Figures A worm 146 is fixed on the left hand end of the ma shaft 14 and meshes with a worm wheel 147 fixed on a sleeve 148 revolubly mounted on a shaft 149. A suitable reduction train 150 Aconnects shaft 149 with the shafts 34 carrying the cams 56. Alower clutch member 151 is' fixed on the n0 alocal relay circuit. A conductor 154 replaces no the conductor 66 and leads from the battery 67 to one terminal of relay magnet 155, which has 'its other terminal connected by* a conductor 156 with the circuit closer 64; A fixed yrelay contact 157 is connected by a conductor 158 with 125 the magnet 71. An amature contact 159 of this relay is connected by a conductor 160 with the ground wire 80. A conductor 70 connects the magnet 71 and the magnet 69 as before. A conone terminal of a relay magnet 162 and a conductor 163 connects the other terminal of this magnet 162 with the supply conductor 75. An armatureor movable contact 164 is closed by the contact 165. A conductor 166 extends from the main supply conductor 75 to contact 78 and a conductor 167 connects the contact 77 with one terminal of the magnet 86. A conductor 168 to ground line 80. A holding magnet 169 is provided for armature contact 164 and a conductor 170 connects said armature contact to one terminal of this magnet. A conductor 171 connects the other terminal of this magnet with the ground line 80. A conductor 172 connects the supply conductor 75 with contact 84. One terminal of magnet 26 is connected by conductor 82 as before, to contact '83, the other terminal vductor 161 connects the magnet 69 in series with 130 connects the other terminal of this magnet 86 no of this magnet being grounded as at 173. A conm motor 12 and this motor is grounded at 175. A

circuit closer 176 is mounted on the disk .or platform 49 in circumferentially spaced relation to the contacts 52 and 53 and is, like them, actu-y ated by the cam 50. A second circuit closer 177 is similarly mounted and is also actuated by cam 50. It is here to be noted that the adjustment of the contacts 52 and 53 in synchronizing the closing of these'contacts with Washington time, also similarly adjusts the circuit closers 176 and 177. A conductor 178 connects circuit closer 176 with conductor -161 and a conductor 179 connects circuit clo'ser 176 with conductor 160 and thusto the ground. A conductor 18) connects circuit closer 177 with' oneside ofI magnet 169 and 'a conductor 181 connects said circuit closer to conductor 170. 4A. conductor 1 81" connects contact 164 Withone terminal of magnet 153 and the'otherI terminal of this magnet is grounded'at 183'.

VIn-this form of the invention the rst set of contacts in the master clock close at twentyy seconds to the hour and the second s et at ten secondsto the hour as before. As the second s'et closes, current will ow from battery 67 through conductor 66, circuit closer 63, conductor 65, circuit closer 64, conductor'156, magnetl 155 and conductor 154 back to the battery. This will cause -closing of contact 159 on contact 15'7 and cur-- rent will flow from supply 75 through conductor 163, magnet v162, conductor 161, magnet 69, conclutch member 152 to drop, so that shafts 34 are and 51 will start to revolve.

ductor 70, magnet 71, conductor 158, contact 157, contact 159 and conductor 160 to ground wire 80. This effects the closing of contact 83 in contact 84, of contact 77 on contact 78 and of contact 164 on contact 1'65. Current will now flow from supply conductor through conductor 172, contact 84, contact 83, conductor 82 and magnet 26 to ground 173 thus-energizing-the magnet 26 and opening the clutch controlled thereby as before. Also current will now from feed 75 through conductor 166, Contact 78,r contact 7.7, conductor 90, conductor 174 and motor l2 to ground 175. From contact 77 current will flow through conductor 167, holding magnet 86 and conductor 168 to ground Wire 88. A conductor 184 connectscontact 77 with contact 165 so that current will also flow from contact 77 through conductor 184, contact 165, contact 164, conductor 182 and magnet 153 to ground 183 thus opening the clutch member 152 from 151. The two clutches controlled by magnets 26 and 153 being opened, the motor 12 Will run idle to acquire its rated speed. Also current will ow from contact'164through conductor 170, holding magnet 169 and conductor 171 to ground Wire 80. As in the first form, the cir.- cuit closer 64 will open at twoseconds to the hourfwhereupon the circuit through the relay magnet 155 Will open, thereby deenergizing magnets 71, 86 and 162 with consequent opening of the circuit through magnet 26 so that the clutch controlledthereby will'engage and the cams 50 The holding magnets 86 and 169 are still energized and continue to maintain circuits through m'otor 12 and vmagnet 153. The circuit closer 177 is now closed byl cam' 56 whereupon the holding magnet 169 is short-circuited through conductors 180 and 181 and clutch magnet 153 is deenergized, allowing now driven from'the motor. Nextv the contacts '53 and 52 are closed andthe synchronizing impulse is sent out as inthe first instance; The

178,' circuit closer-176, conductor 179 and con- `Now current will flw romfeed 75 through conductor 163,. magnet 162, conductor 161, conductor ductor 160. This will 're-establish the circuit throughmag'net 153 and unclutch the' clutch controlled thereby, thus stopping movement of the cams 56. Finally the circuit closer 54 is closed and this short-circuits the magnet asinthe first form and the. motor stops.

It is to be understood'that the individual clock circuits may alsobe used as messenger vcall circuits. This utilization of conductors for two services is possible because of thewidedierence bctween the operating current required for correcting subscribers clocks a'ndthat required` for operating thef 'messenger equipment by means of which calls from patrons are recorded. The cur-- rent required forA the messenger service is about' 95 one-fth of that usually provided for the operation of the resetting mechanism of clocksand is not of sufcient magnitude to affect the clock service. This messenger current Iis continuous except when calls are being received from patrons call boxes. -5

Each combined circuit serves a number of call boxes and in addition, a number of clocks each of which is provided with the electro-magnet to control itsresetting device. The call boxes-and the electro-magnets are connected in series on the vline Wire. A number of these` wires or'circuits are terminated at a central oIice where they are normally connected to the apparatus by meansotwhich Asignals-.from the call boxes are received. Injorder that the call circuit receiving apparatusl at the central oice maybe momentarily disconnected during the transmission of the synchronizing impulse for the clocks, Imodfy the synchronizing impulse device for the clock circuit closers shown in Fig. 4, by adding to each pair of contacts another contact spring which is connected to the calll circuit receiving apparatus, as shown in Fig. 4a. It will be evident that at the instant the cam member 56 rotatesA into position to close the clock circuits, the intermediate spring 4contact arms which 'engage the cam faces will ter clock, a subscribers clock having an el'ectromagnetic clock setting device includingra synchronizing circuit and a normally open circuit closer therefor, a revolving element arranged to engage and close-said circuit closer, a normally inactive motor having a motor circuit and a normally open motor circuit closer, a driving mechanism lconnecting said element and motor and including a normally closed clutch, an electro-- magnet arranged to open the clutch when. energized and'having' a circuit'including a normally open magnet circuit closer, and electro-magnetic means controlled by the master clock forclosing the motor and magnet circuit closers and. for releasing the magnet circuit closer to open prior to the opening of the motor circuit closer.

2. In a clock synchronizing apparatus, a masthe synchronizing circuit at the first mentionedl ter clock, a subscribers clock having an electromagnetic clock setting device including a synchronizing circuit and a normally open circuit closer therefor, a revolving element arranged to engage and close said circuit closer, a normally inactive motor having a motor circuit and a normally open motor circuit-closer, a driving mechanism connecting said element and motor and including a normally closed clutch, an electro-magnet arranged to open the clutch when energized and having a circuit including a normally open magnet circuit closer, magnets for closing said magnet circuit closer and said motor circuit closer respectively, a battery circuit extending through said magnets and including a normally open circuit closer, means controlled by the master clock for temporarily closing the battery circuit closer, a holding magnet for the motor circuit closer having a circuit closed upon closingv of the motor circuit closer, and means for short circuiting the holding magnet circuit.

3. A clock synchronizing apparatus, as set forth in claim 2, and a testing circuit having means to close said relay circuit independent of said motor actuated means to effect closing of circuit closer. Y

4. In a clock synchronizing apparatus, a. master clock, a subscribers clock having an electromagnetic clock setting device, a synchronizing circuit and a normally open circuit closer therefor, a revolving element arranged to engage and close said circuit closer, said circuit closer being adjustable along a path concentric to said revolving element, a motor, an operative connection between said motor and revolving element including a clutch, and electro-magnetic means governed by the master clock for controlling the operation of said motor and clutch.

6. In `a clock synchronizing apparatus. a master clock, a subscriber's clock having an electromagnetic clock 'setting device including a synchronizing circuit and a normally open circuit closer therefor. a revolving element arranged to engage and close said circuit closer, said circuit closer being movable along a path concentric to said revolving element, a normally open relay circuit arranged to eiect preparatory closing of the synchronizing circuit and including a relay circuit closer, a second revolving element arranged to 'engage and close said relay circuit i closer, saidfrelay circuit closer being movable along a path concentric to said second revolvingv element, means to move said circuit closers along said paths simultaneously in equal arcs, a motor, an operative connection between-said motor and revolving elements including a clutch, and electro-magnetic means governed by the master clock for controlling the operation o! said motor 6. In a clock synchronizing apparatus, a master clock, a normally open subscribers clock synchronizing circuit including a plurality of circuit motor for closing said relay circuit, and other means driven by the motor tor closing the synchronizing circuit at a second one of said circuit closers.

'GEORGE W.v J AN SON. 

